Blocking layer electrode system



J 30, 1942- N. w. H. ADDINK 2,288,341

BLOCKING LAYER ELECTRODE SYSTEM Filed June 12, 1940 jIvwsn/ro P 2 fl/wmni flrra FA/EY Patented June 30, 1942 BLOCKIYG LAYER ELECTRODE SYSTEM NicolaasQWillem' Hendrik Addink, Eindhoven, j Netherlands, assignor, by mesne assignments,

to'liartford National Bank and Trust Company, Hartford, Conn, as trustee Application June 12,1940, Serial No. 340,224

In the Netherlands June 2, 1939 11 Claims. (Cl. 175-366) My invention relates to devices comprising a plurality of blocking, layer electrode systems, for v instance dry rectifying cells, which are arranged in a stackv and are artificially cooled by a liquid.

The load capacity, of suchcells. is limited by the maximum'temperature ,to which they may .be heated and if they areheated' to ahigher temperature, they will be deleter'iously affected,

for instance theirlife will be shortened j It is also desirable to keep the temperature of the cells v, within. certain limits, because they frequently contain materials which have a fairly high negative temperature coefficient and the temperature -resp'o'nse of. the cells may be considerable. Thus,

if one increases the load or suchcells, there will such as oil.

.be a greater production of heat and consequently "a higher operating temperature.

temperature1at' a low value, or at least to reduce it, it has been proposed to cool thecellsby cir- .culati'ngair and by placing the same in'a liquid,

To keep "this boils at the maximum admissible temperature of the systems and which need not be artificially circulated, and so arrange the systems that the liquid can penetrate between the portions of the succeeding, systems. g Y

Byusing these measures 1 ensure that as soon as the temperature at these points tends to exceed the admissible value, a large amount of heat is removed immediately from these points at which most of the heat is released. More particularly, the cooling liquid can reach the danger points and the vapor bubbles areimmediatelyevolved-at the points when the admissible temperature is reached.v Consequently, the cooling liquid boils at the points where the largest amount of heat is produced, i. e. points .at which, due to unsatisfactory dissipation of heat, a state of equilibrium between the produced heat and the dissipated heat would establish at a temperature which is higher. than at the other locations of the device.

. H0wever, in accordance with the invention the Although coolingwith a'stream of air or gas is very' simple, it hasjthe drawback thatgases h'ave comp arat'ivel'y small thermal conductivities, and therefore a'large quantity of the same must circulated per unit of time. t stream of 'gasmay contain impurities which d'e-' fposit onthe surface ofithe members being cooled,

In addition a with the result that the cooling becomes less rfective. Furthermore; if the cells are not enclos'ed they may be 'deleteriously affected by gases present in the atmosphere. Although the latter difilculties may be overcome by enclosing" the cells andremoving injurious gases and impurities from the cooling air, such constructions are very complicatedand expensive.

vaporisation of the cooling liquid at these points withdraws such a quantity of heatfrom the electrode system that a state of thermal equilibrium is,established at the temperature at whichgthe liquid boils. Consequently the maximum admissible temperature is not surpassed.-

According to one advantageous embodiment of the invention I so arrange the electrode systems that the cooling liquid penetrates between the cells to such an extent that the entire active surface thereof is in contact with the cooling 1 liquid.

Altho ug "the use of a cooling liquid, such as oil overcomes someo'f the above difliculties,-prior devices using cooling liquids have several disad- -vantages,'for example, certain portions'of the electrode systems may not be properly cooled, even if the liquid is circulated artificially."

'The'main' object of my invention is to overcome the disadvantages of prior gasorliquid cooled devices of the above type.

further object is to increase the load caapacity of artificially cooled blocking layer elec-- trode systems. i

A. still. further object is provide a rnorereliable and efficient method of cooling such sys- .,.tems.' 1

Further, objects and advantages of my inven- ,tionwill appear as the description progresses.

According-to the invention ,1 submerge the V In this way the heat is dissipated as rapidly .as possible throughout the surface at which it is produced. In the usual constructions in whichthe cells are mounted on one or more supporting members extending perpendicular to the planeof ,the electrode-systems, ,I obtain the above results by providing distancing pieces on these supporting members and between the various cells.

To, facilitate the dissipation of heat of each cell I prefer to provide the same withacooling plate which is spaced from the cell. With-this construction the cooling liquid can come in contact with a very large surface area of both the plates and of the cells. For a suitable dissipation of heat from one cell to its corresponding cooling plate I establish good thermal contact between them and for this purpose I prefer to use an arrangement in which the cells and the cooling plates are arranged in a row on a shaft and are spacedapart by annular members which are of t t m ithin a cooling liquid which a material of good thermal conductivity and terial which is applied to the plates or cells so that it is in direct thermal contact therewith. As such a layer may be very thin, the dissipation of heat from the cell will generally not be affected thereby. For this purpose I may use a lacquer layer, and if the parts of the systems or of the cooling plates are made of aluminium, a layer of inert material can be produced also by providing the aluminium with an oxide layer.

I prefer to use a cooling liquid which is not electrically conductive, because this makes it unnecessary to employ special means for screening parts which are alive and are in contact with the liquid. With such liquids the transformer providing for the supply of energy to the cells may be located in the cooled vessel and such an arrangement has I the advantage that the transformer 'is also'cooled and may consequently have a smaller size than whencooling only by air.

In order that the invention may be clearly understood'and readily carried into effect I shall describe the same in more detail with reference to the accompanying drawing in which:

Figure 1 is a sectionized side view of a device according to the invention,

Fig.2 is a sectional view taken along line 2-2 of Fig. 1, and Fig. 3'is a sectional view of a device according to' another embodiment of the invention.

The device illustrated'in Fig. 1 comprises aclosed metal container 6 provided with a pressure relief valve IT. The container is provided on its top and sides with cooling ribs or fins B and is partly filled with a suitable cooling liquid 1.

Submerged in the cooling liquid 1 are a plurality of blocking layer electrode cells, for instance dry rectifiers, which are arranged on a supporting member 2 carried by a U-shaped strip 3 secured to the bottom of container 6. It should be noted that the thickness of the cells I is exaggerated as compared with the diameter in the" drawing. Each of the cells I comprises a disc-shaped support, for instance of aluminium, which has applied to it in the following sequence; a semi-conductive electrode, for instance of selenium, a blocking layer and electrode of good conductivity. Mounted on the support 2 are a plurality of cooling plates 4, for instance of aluminium, which are separated 'from the cells by members which have a small outside diameter and are made of a material of good thermal conductivity, such as nickel or aluthe center of the supporting plate, but only to about the ,edge of member 5 so that the entire rectifying surface is in contact with the cooling liquid.

'the advantage that the heat,

The manner in whichthe cells are electrically interconnected and, if necessary electrically insulated, for instance in a Gratz circuit, is not shown for the sake of simplicity.

The cooling action is brought about by the vaporization of the liquid 1, the heat of vaporization of the liquid being withdrawn from the cells and given up from the vapor when the vapor condenses in the cooling space 9. The condensed liquid then passes back to the bottom part of the vessel. As shown in Fig. l the cooling of the space 9 is further increased by means of a fan H) which circulates the air past the ribs s and la.

is insufficiently cooled.

It should be noted that the cells are completely shut off from the cooling air and therefore the drawbacks mentioned above do not occur. Furthermore, the container 6 is tightly closed so that the liquid cannot escape by vaporization and thus be lost.

Another advantage of the use of a closed vessel is that in selecting the cooling liquid one is not restricted to the use of liquids which have certain boiling points. More particularly, if the maximum .admissible temperature of the cells were 60 C. and the container 6 were open to the atmosphere it would be possible touse only liq- .uids boiling at 60 C. under atmospheric pressure, such as dichlorethylene (B. P. 60 C.) or chloroform (B. F. 61 C.). When using a container in which the pressure may exceed atmospheric pressure, one may also use materials having a lower boiling point, such as acetone (B. P. 56 0.). Conversely one may also employ liquids having a higher boiling point provided that the pressure in the vesselis reduced to below atmospheric pressure, for instance liquids such as methanol (B. P. 64.5" C;), benzene (B. P. C.), methyl-ethyl ketone (B. P. 80 C.) or ethyl alcohol (B. P..'78 C.).

The extremely favorable cooling efiect ob tained with the device according to the invention will be explained in more detail with reference to Fig. 2 which is a side view of one of the cells of Fig. 1. As a rule the cooling effect of liquids in various apparatus is based on the principle that the cooling liquids are heated and consequently rise, whereupon they give off their heat in some way or other and are thus cooled. The stream of cooled liquid descends and the heat produced in the heated object can be absorbed again. In some cases the circulation is expedited by artificial means.

However, from Fig. 2 it appears that thereare so-called heat pockets, particularly over the distancing ring 5, due to which such a location If, coo1ing of the above type were used either the temperature at a point on top the ring 5 wouldbe superheated owing to insufficient cooling at this point with all the detrimental consequences incident thereto, or if this point were kept at the proper temperature,'

the other points of the cell would be cooled to a temperature which would not produce eflicient results. This difliculty is avoided by using a liquid which boils at the maximum temperature admissible; in fact, the quantity of immovable liquid over the ring is made to boil when its temperature exceeds its boiling point due to stronger heating, the quantity of heat withdrawn at this point for vaporization having such a value that superheating does not occur. Consequently the cells can be operated at temperatures up to the maximum admissible temperature with all the advantages thereof and without the drawbacks set out above. In addition all points of the cells are maintained at an efiicient temperature.

The safety valve ll of suitable type is used to avoid inadmissible overpressure in the vessel for some reason or other, due to which the latter may explode. This valve, which may be of the usual type, comprises a valve I8 which is held 'closedby a spring l9--when the pressure of the vapor within space 8 is below a certain value. If, however, the pressure surpasses this, value, the valve opens and some of the gas is allowed to escape. If the pressure of thegas within space 9 is below atmospheric pressure, a valve which opens at a reduced pressure would be used.

From the above it appears that in the device according to the invention, the cooling is essentially based on the withdrawal of evolved heat by liquid which is not essentially circulated, the large amount of heat being obtained to cause the cooling liquid to evaporate, whereas in prior art cooling systems operating, for instance with oil, the cooling is based on convection.

The device shown in Fig. 3 is similar to that of Fig. l and has the same parts indicated by the same reference numerals. However, in Fig. 3 the cooling liquid 1 almost completely fills a container 26 which has an opening 21 connected through a tube [6 and cooling coil I l to an opening 29 in the top of the container. The coil II is located in a second container I2 provided with an inlet opening and an outlet opening l5 for the circulation of a suitable cooling liquid such as water.

In the device the vapors of the cooling liquid 1, which may be benzene, condense in the coil i l and the condensate returns through tube l6 to the bottom of container 26.

When making use of a cooling liquid which attacks the material of the cells or of the cooling plates, or is an electrical conductor, the various parts I, 4, 5 etc., may be provided with a thin container, a cooling liquid within said container,

layer of lacquer, or for instance chlorinated rubber lacquer.

Although I have described my invention with reference to specific examples and applications pressure occurring within the container during operation of the device.

2. A device of the class described comprising a container, a cooling liquid within said container and a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, said systems being spaced apart to allow the penetration of said cooling liquid, the boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device.

3. A device of the class described comprising a container, a cooling liquid within said container, and a plurality of blocking layer electrode systems submerged in said liquid and hava supporting member, a plurality of blocking v layer electrode systems mounted on said member, and means mounted on said member and spacing said systems apart, said systems being submerged in said liquid and having a maximum admissible operating temperature, the boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device.

5. A device of the class described comprising a container, a cooling liquid within said container, a supporting member, a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, a plurality of cooling plates, said plates and systems being mounted on said member and being spaced apart, the boiling point or said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation 0!. the device.

6. A device of the class described comprising a container, a cooling liquid within said container, a supporting member, a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, a plurality of cooling plates, a plurality of spacers of a good heat conducting material, said systems, plates and spacers being mounted on said support with the spacers between'the plates and the systems, the boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device.

7. A device of the class described comprising a container, a cooling liquid within said container, a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, the boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device, and a thin layer of electrical insulating inert material in the surface of said systems.

8. A device of the class described comprising a container, a cooling liquid within said container and a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, the boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device, and a thin layer of lacquer on the surface of said systems.

9. A device of the class described comprising a container, a non-electrically conductive cooling liquid within said container, and a plurality of vvithin the container during operation of the device. g

10. A device of the class described comprising a container, a cooling liquid. Within said container, and a plurality of blocking layer electrode systems submerged in said liquid and having a maximum admissible operating temperature, the

boiling point of said liquid being substantially the same as said operating temperature at the pressure occurring within the container during operation of the device and being different at atmospheric pressure. p

11. A device of the class described comprising a normally+closed container, :3. coolingdiquid within the lower portion of said container, 9. plurality-of bl'ocking'layer electrode systems. submerged in' said liquid and having a maximum admissible operating temperature,- the boiling point of'said liquid being substantially the same as said operating temperature at 'theipressure occurring within the container during. operation of thedevice, and cooling means for condensing the vapors of the cooling liquid produced during operation of the device;- v

NIooLAAs 'WILLEM HENDRIX ADDINK. 

